1. Field of the Invention
The present invention relates to a bending apparatus to bend a long work such as a pipe or a rod. Particularly a bending apparatus in which a work can be fed not only along a horizontal plane but also be moved along a vertical plane against one of plural bending templates of different radii that are placed vertically one upon another.
2. Description of the Prior Art
In one of the apparatuses of the above mentioned type according to the prior art, a work is fed longitudinally into contact with a bending template and is pressed against the bending template by a fastening apparatus which is movable in the direction perpendicular to the longitudinal direction of the work. The template and the fastening apparatus hold the work to be bent closely therebetween and are turned together with the work, by the end portion of a bending link, around the center of curvature of a bend to be formed. The desired portion of the work is thus bent. In the apparatus of this type, however, the radii of curvature of bends to be formed on plural portions of the work are all the same or otherwise the bending template must be exchanged each time if bends of different radii of curvature are to be formed. The operation of exchanging templates takes a long time and is very troublesome. Furthermore, relative positions of a series of bends to be formed on the same work apt to be inaccurate since an old bending template must be removed from a mount axis thereof in order to exchange bending templates, and the work and the fastening apparatus have to be positioned against a new bending template.
As an apparatus in which the above mentioned problems have been settled, a bending apparatus is known which is provided with a series of bending templates of different radii arranged coaxially around a vertical axis and movable axially. Since each of the bending templates of such an apparatus needs a certain radial thickness, it is impossible to select an arbitrary radius for each template and the radii of templates become considerably discrete. For this reason it is impossible with this apparatus to form some bends of arbitrarily close radii. Furthermore, a play for insertion and axial displacement must be formed between two adjacent bending templates disposed coaxially. When a bending template of a large radius is used, several plays of the above mentioned type, for some bending templates of smaller radii located inside the template, are added one after another, resulting in a larger play and precise bending operation can not be expected.